1. Field of the Invention
The present invention relates to particle radiation therapy systems and, in particular, to the access floor surrounding a patient table within a rotating gantry system.
2. Description of the Related Art
Particle radiation therapy involves coordinating complex systems and devices to enable targeting of specific cancerous regions of a patient. In particular, proton beam therapy utilizes one or more precisely aligned particle streams to irradiate cancer or tumor cells. The energized protons disrupt targeted cells or tissue so as to effectively halt the progression of the disease. In proton beam therapy, the patient must be accurately positioned with respect to the one or more beams so that the stream irradiates only the desired target region, otherwise the stream may damage healthy cells within the patient's body. Specific alignment in this manner requires numerous control systems to maintain accurate and precise dosage delivery to a plurality of patients during prescribed treatments.
As described in U.S. Pat. No. 4,870,287, a proton treatment facility generally comprises a proton energy source, an injector, an accelerator, a beam transport system, a switchyard, and a plurality of treatment stations so as to accommodate multiple patients. Each treatment station may comprise a plurality of treatment components such as treatment platforms, gantry structures, and patient monitoring components. Additionally, control and monitoring of the proton treatment facility may be directed by computer and hardware subsystems, which coordinate the activities of each treatment station using software configurable components.
Moreover, control system activities may include beam intensity management, beam position orientation and modification, digital imaging performance, safety condition monitoring, and various other treatment functions. Together these systems form a highly complex collection of hardware and software components. The complexity of the proton treatment facility may be further magnified by managing multiple treatment stations where additional requirements for system redundancy and selective control of each treatment station is required.
The preferred position for a patient is the supine position so as to preclude any deformation of the organs during treatment. Therapy must therefore allow accessibility from all sides and encompass the entire human body. For this reason, the generally known proton therapy devices, are designed so that the entire proton beam guiding device housing is rotatable through 360 degrees about a central axis around a patient table that is aligned with that central axis. A typical proton treatment room includes the treatment system 10 shown in FIGS. 1-2. In this system, a rotating gantry 12 supports a beam nozzle 14 contained within a support housing 15. Protons from a remote source are directed by beam deflectors to the nozzle 14 to effect treatment of a patient P (FIG. 2) supported on a patient table T. The rotating gantry is a very large structure, typically measuring 40 feet in diameter at its largest extent, and about 20 feet in diameter at the mouth of the gantry. The table T is cantilever supported within the mouth of gantry 12 so that the entire gantry structure and nozzle 14 can rotate a complete 360° around the patient.
Safety considerations dictate the need for a floor adjacent the patient table. Moreover, the floor provides access to the patient table by radiation treatment technologists and medical personnel during setup of the treatment facility, positioning of the patient on the table, and sometimes during a treatment. The presence of the massive rotating gantry 12 is at odds with the need for complete access around the patient table T within the rotating gantry structure. In particular, any platform or floor providing access to the patient table will necessarily interfere with the necessary rotation of the gantry about eh patient. There is a significant need for a floor assembly that can be used with a large rotating gantry facility to provide immediate patient access without interfering with the operation of the gantry.